Terahertz time-domain spectroscopy (THz-TDS) was used to measure the information of water, the terahertz time-domain and frequency spectroscopy, absorbance, refractive index and the complex dielectric permittivity in the frequency range of 0.2～1 THz of various hydrated TiO2 samples with heating for different times. The result reveals that the absorbance of hydrated TiO2 reduces with heating time increasing, and the location of the absorption peak is corresponded to the refractive index. The response of electric polarization in THz field has no clear relations with the frequency. With frequency increasing, the dielectric dissipation of hydrated TiO2 firstly decreases and then tends to be stable. The dielectric response always reduces with heating time increasing.